Process for producing an improved asphalt



United States Patent 3,131,140 ERQCESS FGR PRODUCENG AN E/[PRGVEDASPHALT Herbert James Brice, In, Harold George Houlton, and Stuart HenryMorgan, Ashiand, Ky., assignors to Ashland Gil & Refining Company,Ashland, Ky., a corporation of Kentucky No Drawing. Filed Apr. 13, 1961,Ser. No. 102,629 14 Claims. (Cl. 2084) This application relates to aprocess for producing an improved asphalt which demonstrates excellentadhesion to a galvanized or other metal surface, and more particularlyrelates to a process for producing an improved asphalt for use as a pipeor culvert coating material which is able to withstand extreme changesin temperature under severe conditions of use, and which retains over aprolonged period strong adherency to a metal surface onto which it iscoated.

For many years it has been conventional to coat metal pipes andparticularly galvanized metal culverts and the like with a bituminous orasphaltic material to improve their serviceability and prolong theiruseful life. Culverts in particular are exposed in use to extremeconditions of temperature and climate, are subjected to the erodingaction of the water which they are utilized to carry, and are normallyexpected to function without significant repair for a life of perhapsforty years. The asphaltic coating is applied to protect the underlyingmetal from direct contact with its environment, and thereby preserve itsstructural qualities for a much longer period than would otherwise bepossible.

To be satisifactory as a pipe or culvert coating material, an asphaltmust possess several qualities which are to a certain extentinconsistent with each other. It is of primary importance, of course,that the asphalt adhere strongly to the metal surface, and that theadhesive bond does not deteriorate greatly over a long period of timeunder the effects of the severe conditions of use to which the coatingis exposed.

In addition to adhesion, another important criteria of the quality of acoating asphalt is its consistency, both as applied and after aging.Consistency is quantitatively measured in the industry in terms ofpenetration and softening point, as determined by means of standard testmethods referred to hereinafter. Moreover, the asphalt should displaygood resistance to softening under the efi'ects of heat, as well as goodresistance to the adverse efiects of cold.

Pipe or culvert coating asphalt has heretofore been made from crudepetroleum by vacuum distilling a reduced crude petroleum, residual oilor comparable material, to yield what is referred to in the industry asa straight run or vacuum reduced asphalt. Generally speaking, straightrun asphalt is too soft in consistency for use as a culvert coatingmaterial. In the past it has been conventional to harden the softstraight run material to a desired consistency by a process ofoxidation. This oxidation process is called blowing, and is effected byblowing a stream of gas, usually air, through the material to beoxidized, usually at an elevated temperature. The asphalt is therebygradually made harder, the blowing eing terminated when the asphaltattains the desired degree of hardness. Cylinder stock, which is a sidestream from an asphalt vacuum tower, can be also blown to produce asynthetic asphalt of desired consistency. The culvert coating asphaltsheretofore produced have usually comprised straight run asphalt,cylinder stock, or a mixture or flux of the two which has been blown oroxidized to a desired consistency.

In general, asphalts produced by the conventional 3131,14 Patented Apr.28, 1964 ice processes of the past have been satisfactory as toconsistency but have been deficient or poor in their adhesion to a metalsurface, and have not provided a satisfactory longlasting bond to themetal surface. Specifically, asphaltic coating materials of the pasthave displayed poor adhesion to galvanized metal surfaces, and havetended to chip or crack off from the surface under the effects ofclimate changes, as a result of which such asphalts have affordedrelatively poor protection to the metal onto which they were coated.

This application is directed to an improved process of producing anasphalt for coating pipes and the like which displays much betteradhesion than materials heretofore available as well as properconsistency, and which is capable of withstanding severe conditions ofuse, climatic changes, and erosion.

The process we have discovered and empirically determined is based onthe concept of blowing or oxidizing a cylinder stock to a consistencywhich is harder than ultimately desired, and then fluxing back orblending the overblown stock with a straight run asphalt to yield aproduct having the desired qualities. Otherwise put, we have found thatby blowing a cylinder stock having a viscosity within a specified rangeto a consistency much harder than normal coating materials, and thenmixing this material in certain proportions with a straight reducedasphalt of prescribed consistency, it is possible to produce a blendwhich is of desirable consistency and which, moreover, displays muchgreater adherency to metal surfaces than conventional asphalt.

The viscosity of the cylinder stock should be in the range of about to190 SUS at 210 F., as measured by the standard test procedure defined inASTM test No. D.88-44. Preferably, this cylinder stock should be from apetroleum of Mid-Continent origin, tests indicating that the finalproducts made from such stocks are generally of somewhat higher quality.Where an Eastern cylinder stock is employed, it is preferred that itsviscosity be in the range of about -190 SUS at 210 F.

The technique of blowing is Well known to those skilled in the art, forwhich reason it is believed unneces sary to describe it in detailherein. The cylinder stock is blown in accordance with conventionalpractice, preferred conditions being a temperature of 440470 F. and anair flow of 0.02-0.05 cubic feet per minute per gallon of cylinderstock.

The cylinder stock is blown until it has a penetration, as measured bythe standard test defined in ASTM test No. D-549, in the range of 3550at test conditions of 77 :F., 100 grams weight, and five seconds time,and until it has a softening point, as measured by the standard testprocedure defined in ASTM test No. D-3626 (ring and ball method), of230260 F. A cylinder stock blown to these conditions would, according topast practice, be deemed far too hard to be suitable as a culvertcoating material.

The asphalt to be blended with the blown cylinder stock should be astraight run asphalt having a penetration in the range of 70-100, and isadmixed with the blown cylinder stock in the amount of about 5 to 20% byvolume. It appears preferable from present evidence that this asphalt beof the same geographical origin as the cylinder stock.

Following are examples of the practice of the process we havediscovered:

Example I A cylinder stock having a viscosity of SUS at 210 F. isproduced by the vacuum distillation of reduced crude petroleum.

This material is blown until it has a penetration of 45 and a softeningpoint of 234 F. To the blown cylinder stock is added 15% by volume of astraight reduced asphalt having a penetration of about 75. The mixing orfluxing step may be carried out in any conventional manner. Theresulting product has a penetration of 50 and a softening point of 208F., demonstrates exceptionally good adhesion to a metal surface, and isan excellent coating asphalt.

Example 11 An Eastern cylinder stock having a viscosity of 121 SUS at210 F. was blown to a softening point of 245 F. and a penetration of 43.With this oxidized product was fluxed 8% y volume of a straight runasphalt having a penetration of 85, yielding an asphalt having asoftening point of 206 F. and a penetration of 48, and demonstratingexcellent adhesion to a galvanized metal surface.

Example III An Illinois cylinder stock having a viscosity of 150 SUS at210 F. was blown to a softening point of 242 and a penetration of 40.This material was blended with 15% straight run asphalt having apenetration of 73. The resulting product had a softening point of 20 8and a penetration of 43, and exhibited excellent adhesive properties andweathering characteristics.

Example IV An Illinois cylinder stock having a viscosity of 185 at 210F. was blown to a softening point of 244 and a penetration of 39.Blending with 20% straight run asphalt having a penetration of 90 gave amaterial having a softening point of 201 and a penetration of 48 whichshowed excellent adhesion and weathering properties.

Example V A Louisiana cylinder stock having a viscosity of 152 at 210 F.was blown to a softening point of 240 and a penetration of 40. Thismaterial blended with 20% Louisiana straight run asphalt of 85penetration resulted in a blend having a softening point of 204 and apenetration of 46 which showed very good adhesive properties.

Example VI A Louisiana cylinder stock having a viscosity of 184 at 210F. was blown to a softening point of 240 and a penetration of 36. Whenblended with 20% Louisiana straight run asphalt of 85 penetration, anasphalt was produced with a softening point of 200 and a penetration of41. This blend had good adhesive properties.

Example VII A11 Eastern cylinder stock having a viscosity of 174 at 210F. was blown to a softening point of 230 and a penetration of 45. It wasblended with straight run asphalt of 70/ 80 penetration, resulting in amaterial with a softening point of 205 and a penetration of 50 whichdisplayed excellent adhesive properties.

Example VIII 1. A process for producing an asphalt which demon-' strateshigh adhesion to a metal surface, said process comprising, blowing acylinder stock having a viscosity of about 110 to 190 SUS at 210 F. to asoftening point of about 230 F. to 260 F. and a penetration of about 35to 50, and fluxing the blown cylinder stock with about 5 to 20% byvolume of a straight reduced asphalt having a penetration of about 70 to100.

2. The process which comprises, oxidizing a cylinder stock having aviscosity of about 110 to 190 SUS at 210 F. to a softening point ofabout 230 F. to 260 F. and a penetration of about 35 to 50, and blendingthe oxidized cylinder stock with about 5 to 20% by volume of a straightreduced asphalt having a penetration of about 70 to to yield an asphalthaving a softening point of about 200 'F. to 220 F. and a penetration ofabout 38 to 52.

3. A process in accordance with claim 2 in which said cylinder stock isa straight run cylinder stock.

4. A process in accordance with claim 2 in which said cylinder stock isfrom a crude petroleum of Mid-Continent ongm.

5. A process in accordance with claim 2 in which said cylinder stock andsaid straight reduced asphalt are from crude petroleum of the samegeographical origin.

6. A process in accordance with claim 2 in which said oxidation isefiected by blowing air through said cylinder stock, said cylinder stockbeing at a temperature of about 440 F. to 470 F.

7. A process in accordance with claim 2 in which said oxidation iseifected by blowing air through said cylinder stock at a rate of about0.02 to 0.05 cubic foot per minute per gallon of cylinder stock, saidcylinder stock being at a temperature of about 440 F. to 470 F.

8. A process for producing an asphalt which demonstrates high adhesionto a metal surface, said process comprising, blowing a cylinder stockhaving a viscosity of about to 190 SUS at 210 F. to a softening point ofabout 230 F. to 260 F. and a penetration of about 35 to 50, and fluxingthe blown cylinder stock with about 5 to 10% by volume of a straightreduced asphalt having a penetration of about 70 to 100.

9. A process for producing an asphalt which demonstrates high adhesionto a metal surface, said process comprising, blowing a cylinder stockhaving a viscosity of about 11 0 to 190 SUS at 210 F. to a softeningpoint of about 230 F. to 260 F. and a penetration of about 35 to 50, andfluxing the blown cylinder stock with about 10 to 20% by volume of astraight reduced asphalt having a penetration of about 70 to 100.

10. A process for producing an asphalt which demonstrates high adhesionto a metal surface, said process comprising, blowing a cylinder stockhaving a viscosity of about to SUS at 210 F. to a softening point ofabout 230 F. to 260 F. and a penetration of about 35 to 50, and fluxingthe blown cylinder stock with about 5 to 2 0% by volume of a straightreduced asphalt having a penetration of about 70 to 100.

11. A process for producing an asphalt which demonstrates high adhesionto a metal surface, said process comprising, blowing a cylinder stockhaving a viscosity of about 110 to 190 SUS at 210 F. to a softeningpoint of about 230 F. to 260 F. and a penetration of about 35 to 45, andfluxing the blown cylinder stock with about 5 to 20% by volume of astraight reduced asphalt having a. penetration of about 70 to 100.

12. A process for producing an asphalt which demonstrates high adhesionto a metal surface, said process comprising, blowing a cylinder stockhaving a viscosity of about 110 to 190 SUS at 210 F. to a softeningpoint of about 230 F. to 260 F. and a penetration of about 35 to 5 0,and fluxing the blown cylinder stock with about 5 to 20% by volume of astraight reduced asphalt having a penetration of about 70 to 90.

13. A process for producing an asphalt which demonstrates high adhesionto a metal surface, said process comprising, blowing a cylinder stockhaving a viscosity of about 110 to 190 SUS at 210 F. to a softeningpoint of about 230 F. to 245 F. and a penetration of about 35 to 50, andfluxing the blown cylinder stock with about to by volume of a straightreduced asphalt having a penetration of about to 100.

14. The process which comprises, blowing a straight run cylinder stockat a temperature of about 440 F. to 470 F. and having a viscosity ofabout to SUS at 210 F. with air at a rate of about 0.025 cubic foot perminute per gallon of cylinder stock until said cylinder stock has asoftening point of about 230 F. to 260 F. and a penetration of about 35to 50, and blending the oxidized cylinder stock With about 5 to 20% byvolume of a straight reduced asphalt from crude petroleum of the samegeographical origin as said cylinder stock and having a penetration ofabout 70 to 100, to yield an asphalt having a softening point of about200 F. to 230 6 penetration of about 38 to 52, and demonstrating strongadhesion to a metal surface.

References Cited in the file of this patent UNITED STATES PATENTS2,029,290 Bray et al. Feb. 4, 1936 2,252,111 Batchelder Aug. 12, 19412,308,245 Ortynsky Jan. 12, 1943 2,317,150 Lovell et al. Apr. 20, 19432,785,111 Vierk Mar. 12, 1957 OTHER REFERENCES Asphalts and AlliedSubstances, by Herbert Abraham, chapter 8, volume 2, page 172-5, SixthEdition, D. Van

F., a 15 Nostrand Co., Inc., Princeton, New Jersey, June 1961.

1. A PROCESS FOR PRODUCING AN ASPHALT WHICH DEMONSTRATES HIGH ADHESIONTO A METAL SURFACE, SAID PROCESS COMPRISING, BLOWING A CYLINDER STOCKHAVING A VISCOSITY OF ABOUT 110 TO 190 SUS AT 210*F. TO A SOFTENIG POINTOF ABOUT 230*F. TO 20*F. AND A PENETRATION OF ABOUT 35 TO 50, ANDFLUXING THE BLOWN CYLINDER STOCK WITH ABOUT 5 TO 20% BY VOLUME OF ASTRAIGHT REDUCED ASPHALT HAVING A PENETRATION OF ABOUT 70 TO 100.